Hydraulic blanking press



Oct. 22, 1963 P. J. LINDNER HYDRAULIC BLANKING PRESS 2 Sheets-Sheet 1 Filed July 15, 1960 INVENTORQ- FAI/z/P [IA/0416B BY Oct. 22, 1963 Filed July 15, 1960 P. J. LINDNER HYDRAULIC BLANKING PRESS 2 Sheets-Sheet 2 IN V EN TOR. l y/u; J [M D/Vi? United States Patent 3,107,567 HYDRAULIC BLANKING PRESS Philip J. Lindner, Mount Gilead, Ohio, assignor to Koehring Company, Milwaukee, Wis., a corporation of Wisconsin Filed Italy 15, 1969, Ser. No. 43,164 4 Claims. (Cl. 83-424) This invention relates to hydraulic blanking presses and concerns, more particularly, a control and operating system for such presses.

In recent years, increased attention has been given the use of triple-action presses for blanking or punching operations. A triple-action press first clamps the stock rigidly, secondly, squeezes the workpiece portion of the stock and thirdly, separates the work piece from the stock. The stock material is thus under compression during the blanking operation and, as a result, the work piece shears cleanly from the stock, eliminating the need for a secondary shaving or trimming operation.

Hydraulic pressure is particularly well suited for tripleaction presses since it allows the required critical adjustment of pressures to obtain the proper compression of the material for effective operation. In addition, hydraulic presses have other inherent advantages over mechanical presses such as making die shimming adjustments unnecessary. However, hydraulic triple-action presses have not heretofore been capable of high speed operation and hence their commercial use has been limited.

It is, therefore, the primary aim of the present invention to provide a very high speed, triple-action hydraulic blanking press.

A collateral aim of the invention is to provide such a press having a shock-free driving system despite the high speeds of operation capable of being obtained.

It is also an object of the invention to provide a press as characterized above in which precise adjustments of the pressures developed and of the operating speed and sequence can be made so that the press is exceptionally versatile and flexible in operation and hence well suited for commercial use.

Moreover, it is an object to provide a press of the above type which is simple to adjust and operate.

It is also an object to provide a press as described above which is economical in design so as to be relatively inexpensive to both manufacture and operate.

Other objects and advantages of the invention will become apparent upon reading the following detailed de scription and upon reference to the drawings in which:

FIGURE 1 is a perspective View of a press embodying the invention;

FIG. 2 is a fragmentary section taken approximately along the line 22 of FIG. 1; and

FIG. 3 is a schematic diagram showing the control and operating system embodied in the press appearing in FIG. 1.

While the invention will be described in connection with a preferred embodiment, it Will be understood that I do not intend to limit the invention to that embodiment. On the contrary, I intend to cover all alternatives, modifications and equivalents as may be included within the spirit and scope of the invention as defined by the appended claims.

Turning first to FIG. 1, there is shown a hydraulic blanking press embodying the invention and including a frame 11 made up of a base 12, a table 13 and a head 14 supported above the table by a plurality of posts or columns 15. A reciprocating platen 16 is mounted on slide portions of the columns 15 for movement perpendicularly with respect to the table 13. A blanking die set 29 is mounted between the table 13 and the relatively movable platen 16 (see FIG. 2).

As a feature of the invention, the table 13 is sharply inclined with respect to a horizontal plane so as to facilitate stripping and clearing the Work pieces from the press following the blanking operation. In the illustrated embodiment, the table 13 inclines rearwardly at approximately a 30 angle and a chute 21 is provided extending from a point adjacent the dieset 20 on the table 13 rearwardly of the machine. In this way, once the work piece is cleared from the die set, it falls under the force of gravity onto the chute 21 and is easily discharged from the press.

For driving the platen 16, a pair of double-acting main rams 25 and 26 are mounted in the press frame head 14 and are rigidly secured to the platen. The rams 25, 26 cooperate with hydraulic ram cushions 27, 28, respectively, at their upper ends which limit upward travel of the platen 16 without shock. Sets of cooperating stops 29 limit downward movement of the platen.

The platen 16 carries a single-acting clamping ram 30 mounted within a housing 31 secured to the upper surface of the platen between the main rams 25, 26. Upward movement of the ram 30 is limited by its fit within the housing 31. Downward movement of the clamping ram is limited by engagement between a head 32 carried by the ram and the bottom of a recess 33 formed in the upper surface of the platen and within which the head 32 reciprocates.

Mounted within the press table 13 is a single-acting cushion ram 35 having a head portion 36 which reciprocates within a chamber 37. The movement of the cushion ram 35 is limited by the confines of the chamber 37 within which the ram head 36 moves.

Hydraulic connections, shown in more detail in FIG. 3, are provided for hydraulically driving the clamping ram 39 in a downward direction, the cushion ram 35 in an upward direction, and the double-acting main rams 25, 26 in either an upward or a downward direction.

Turning now with more particularity to the die set 20, the die set includes a base 41 fixed to the table 13 and carrying a die 42 having a central die opening. The die 42 surrounds a relatively movable die cushion 43 which fits closely within the die opening. A plurality of rods 44, together with a block 45, provide a direct thrust connection between the cushion 43- and the cushion ram 35. When the cushion ram 35 is in its upward limit position, the upper surface of the cushion 43 is flush with the upper surface of the die 42.

Operatively disposed above the die 42 is a punch 48 mounted on a block 49 which is guided for reciprocating movement relative to the die base 41 by a plurality of pins 50. A thrust connection between the punch 48 and the platen 16 is provided by abutment of the platen with the upper surface of the block 49.

For clamping the material during the blanking operation, a clamping plate 55 closely surrounds the punch 48 and is relatively movable with respect thereto. The clamping plate is suspended by headed pins 56 from the block 49. A direct thrust connection between the clamping ram 30 and the clamping plate 55 is provided by a plurality of rods 57 slidably fitted both through the block 49 and the platen 16 so as to abut the head 32 carried by the clamping ram.

In accordance with the invention, operation of the press 10 is controlled by directing hydraulic fluid from both high and low pressure sources to the rams 25, 26, 30 and 35 through a bank 60 of cam controlled valves (see FIG. 1) operated in proper sequence by a plurality of cams phased on a single cam shaft 61. The valve bank 60 is mounted on the press frame head 14 so that the valves are closely coupled to the main rams 25, 26 and the clamping ram 30 of the press and, in this way, ram reaction time is minimized and rapid operation of the press is greatly facilitated. As will be explained below, the cushion ram 35 remains charged during most of the operating cycle and hence its relatively greater distance from the valve bank 60 has virtually no delaying effect on the operating speed of the press.

In the preferred embodiment, the valve bank 60 includes three valves 62, 63 and 64. With more specific reference to FIG. 3, the valve 62 is a two-position, twoconnection shut-off valve having positions 62a and 62b. The valve 63 is a three-position, four-connection directional valve having positions 63a, 63b and 630. The valve 64 is a two-position, threeconnection directional valve having positions 64:: and 64b.

The valves 62, 63, 64 are operated by cams 65, 66 and 67, respectively, through cam follower and push rod assemblies 68 (see FIGS. 1 and 2). It can be readily seen that the shape of the earns 65, 66, 67, and their angular phasing on the common cam shaft 41, dictates the proper sequence of operation for the press and that the timing of the several rams which operate the press can be precisely and easily adjusted by simply adjusting the angular positions of the cams. The positive mechanical connections between the cam shaft 61 and the several valves in the valve bank 60 assures that a proper sequence of operation, once obtained, is maintained throughout the operating run of the press.

For driving the cam shaft 61, a variable speed motor 70 is mechanically coupled to the cam shaft through connections 71. A regulator valve 72 controls the input of hydraulic fluid under pressure to the motor 70 and thus dictates the speed at which the motor is driven. Since the operating speed of the press 10 is dictated by the rotational speed of the cam shaft 61, the press speed can be selected by simply adjusting the speed of the motor 70. Alternatively the speed of the cam shaft 61 could be varied by means of a mechanical speed reducer.

To provide a low-pressure, high-volume source of hydraulic fluid, a pump 75 is coupled to a motor 76 and connected by a hydraulic fluid reservoir 77. The pump 75, when driven by the motor 76, delivers fluid under pressure from the reservoir 77 through a check valve 73 to a low-pressure accumulator 79.

To provide a high-pressure source of hydraulic fluid, a pair of pumps 82 and 83 are each connected to the reservoir 77 and are driven by the motor 76 and a second motor 84, respectively. The pumps 82, 83, when driven by their respective motors, deliver fluid under high pressure from the reservoir 77 through a check valve 35 to a high-pressure accumulator 86.

For regulating the pressure build-up in each of the accumulators 79 and 86, the accumulators are associated with pressure responsive switches 87 and 88, respectively, which control solenoid operated shut-off valves 89 and 90. The valves 89 and 90 are normally open and connect the pumps 75, 82 and 83 to a sump 9 1 for the hydraulic system of the press. When solenoids 92 and 93 are energized from a source of electric current 94, the valves 39 and 90 are shifted to their closed positions whereupon the hydraulic pumps are able to charge their respective accumulators 79 and 86. When a predetermined pressure is reached, the pressure responsive switches 87 and 88 start timers 95 and if the predetermined pressure is maintained for a short interval, for example ten seconds, the switches 87, 88 are effective to break the solenoid circuits and thus deenergize the solenoids 82 and 83. As a result of this arrangement, the pumps 75, 82, 83 are able to build up and maintain desired pressure levels in the accumulators 79, 86 for operation of the press rams. However, in the event that the press remains idle, the output of the pumps is discharged, at no pressure, directly to the system sump 91 and, of course, eventually to the reservoir 77.

In order to accurately control the compression forces exerted on the stock during the blanking operation, both the clamping ram 30 and the cushioning ram 35 are associated with relief valves 101 and 102, respectively, which are capable of being accurately set by servos 103 from a pressure control station 104. In a practical case, the servos 103 can be air-operated with the air pressures being adjusted and visually indicated at the station 104 so as to provide a particularly convenient way of setting and reading the hydraulic pressures exerted on the rams 30 and 35 (see also FIG. 1).

To supply controlled amounts of hydraulic fluid to the rams 30, 35, pressure regulation valves 105 and 106, respectively, are provided in hydraulic lines between the high-pressure accumulator 86 and the respective rams. The regulator valves 105, 106 are set to deliver fluid at a pressure slightly lower than the relief pressure at which the valves 101, 102 are set. Therefore the relief valves 101 and 102 control the compressive forces exerted on the work during operation of the press, in the manner made plain below, and the valves 105, 106 control the supply of fluid to the ram circuits.

The remaining connections of the press control circuit can be best described by briefly reviewing a complete cycle of press operation. To begin operation of the press, the motors 76 and 84 are started and the solenoids 92 and 93 energized so as to drive the pumps 75, 82, 33 and charge the low-pressure accumulator 79 and the highpressure accumulator 36. Initially, valve 62 is in its closed 62b position. Valve 63 is in its 63:: position so as to direct fluid from the low-pressure accumulator 79 through a check valve 110 and to the underside of the double-acting main rams 25, 26. This elevates the platen 16 to its starting position.

The valve 64 is initially in its 64!; position so as to direct fluid from the high-pressure accumulator 36 to the cushion ram 35, thereby holding the cushion 43 in its elevated position flush with the die 42. It will also be seen that the regulator valve 105 is in direct communication with the clamping ram 30 so that the clamping plate 55 is held, by high pressure fluid, in its lowermost limit position.

To begin operation of the press, the variable speed motor 70 is energized so as to start rotation of the cam shaft 61. The cam 66 first comes into play by shifting the valve 63 to its position 63c so that fluid from the low-pressure accumulator 79 is directed to the top of the main rams 25, 26 and the fluid from beneath these rams is vented to the sump 91. This drives the platen 16 downwardly at high speed.

As downward movement of the platen causes the punch 48 to approach the die 42, further movement of the cam shaft 61 causes the cam 65 to shift the valve 62 to its 62a position, whereupon fluid under high pressure from the accumulator 86 is directed above the rams 25, 26. The low-pressure line from the accumulator 79 through the valve 63 remains open but backflow through this line is prevented by the check valve 110. It is important to note that fluid is not being drained from the accumulator 79 during this time interval, and hence the pump 75 has an opportunity to recharge the accumulator for subsequent operation of the press.

The downward pressure of the punch 48 is opposed by the cushion 43 through the stock material, thus compressing the work piece, and the surrounding portions of the stock material are compressed between the clamping plate 55 and the die 42. Thus, both the work piece being blanked and the surrounding stock material are subjected to compressive forces as is the operating mode of a triple-action press. It can be seen that the compressive force exerted on the work piece itself is controlled by the relief valve 102, while the compressive force exerted on the surrounding blank material is dictated by the setting of the relief valve 101. In this way, the press can be set for proper blanking action with dilferent materials of varying size by simply setting the valves 101, 102 from the station 104.

As soon as fluid from the high-pressure accumulator is admitted to the top of the rams 25, 26, the greater force exerted by these rams lowers the cushion 43 against the resistance of the cushion ram 35 and drives the punch 48 into the stock thus shearing the work piece from the surrounding stock. Throughout the shearing operation, the exact desired compression forces are exerted on both the work piece and the surrounding stock since the relief valves 101, 102 maintain their predetermined pressures on the stock and work piece upon upward movement of the clamping ram 30 as the plate 55 is arrested by the die 42 and downward movement of the cushion ram 35 under the force of the punch 48.

Following the actual blanking operation, the continuously rotating cam shaft 61 causes all three of the cams 65, 66, 67 to shift their respective valves. The valve 62 is shifted to its 62b position thereby cutting off the flow of high-pressure fluid to the main rams 25, 26. The valve 63 is shifted to its 63b position thereby decompressing the high-pressure fluid charging the main rams. The valve 64 is shifted to its 64a position so as to decompress the ram 35 by discharging the ram directly to the sump 91. It is important to note that in this interval of press operation, there is no flow of fluid from the high-pressure accumulator 86, and thus the pumps 82, 83 have an opportunity to recharge this accumulator. Also during this period, the low-pressure accumulator 79 continues to be recharged.

Further rotation of the cam shaft 61 causes the cam 66 to shift the valve 63 back to its initial 63a position thereby directing low-pressure fluid to the underside of the rams 25, 26 so as to reelevate the platen 16. Since the clamping plate 55 and the clamping ram 30 are carried by the platen 16, upward movement of the platen draws first the punch 48 and then the clamping plate from the work. The clamping ram 30 automatically returns to its initial down position as the platen 16 is elevated since the regulator valve 105 is set for a slightly lower pressure than the relief valve 101 and more fluid is supplied to the clamping ram circuit as soon as the upward stock compressing force on the plate 55 is relieved.

As a final step upon completion of one full revolution of the cam shaft 61, the cam 67 (returns the valve 64 to its initial 64b position thereby directing fluid from the high-pressure accumulator 86 to the cushion ram 35. This elevates the cushion 43 to the level of the die 42 and thus positively ejects the workpiece from the die. It will be noted that the return of the valve 64 to its 64!) position is slightly delayed with respect to the return of the valve 63 to its 63a position so as to avoid pushing the work piece back into the surrounding stock material.

It will be appreciated that the above-described se quence of operations occurs very quickly and, indeed, a practical press embodying the invention can function at approximately 125 cycles per minute. The operating speed of the press is, of course, dictated by the cam shaft driving speed of the motor 70 and the single cam shaft, with its positive mechanical connections to the control valves 62, 63 and 64, provides precise timing of the press operating sequence at whatever speed the press is operated.

Those skilled in the art will also understand that the cam shaft 61 can be used to operate, and thus properly time, a stock feeding device of any desired type as well as control a work piece clearing unit such as an air blast ejector.

In addition to the high speed effect of the rapid and precise sequencing afforded by the cam control of the operating valves, the high speed of the press also results from positioning the valve bank 60 close to the main rams 25, 26, and from using low-pressure, high-volume fluid to move the main rams while calling upon highpressure fluid only to perform the actual punching operation. In addition, the fact that the accumulators 79, 86 are given time for recharging in the press operating cycle,

and that the operating rams are charged at all times, matenially contributes to the high speed of the press. High press speed also results from carrying the clamping ram 30 on the platen 16 which is actuated by the fast moving main ramsZS, 26.

Shock free operation, in spite of high cycling speeds, results from using low fluid pressures for rapid positioning and high pressures for actual metal working. In addition, giving the accumulators time to recharge con tributes to smooth power flow. To further minimize hydraulic shock, an accumulator is associated with the sump discharge outlet of the high pressure lines.

While the press 10 has been described in use with a blanking die set 20, it will, of course, be appreciated that the invention can be employed with equal effectiveness in a press performing similar operations such as draw forming or severing.

I claim as my invention:

1. In a hydraulic press having a fixed die surrounding a shiftable die cushion and a movable punch surrounded by a relatively shiftable clamping plate, the combination comprising, a cushion ram for holding said cushion, a double-acting main ram for driving said punch toward said fixed die, a clamping ram carried by said main ram for urging said clamping plate towards said fixed die, a low-pressure, high-volume source of fluid under pressure, a high-pressure source of fluid under pressure, means including a pressure regulator for directing fluid from said high-pressure source to said clamping ram at a preset pressure, means including a pressure regulator and a first valve having a first position for directing fluid from said high-pressure source to said cushion ram at a predetermined pressure, means including a second valve having a first position for thereafter directing fluid from said low-pressure source to said main ram to rapidly drive said punch and said clamping plate toward said die, means including a third valve for directing fluid from said high-pressure source to said main ram as said punch reaches said die so as to drive the punch through the stock against the resistance of said cushion ram, said first and second valves having a second position for subsequently exhausting high-pressure fluid from said main ram and said cushion ram following movement of said punch into said die, said second valve having a third position for directing fluid from said low-pressure source to said main ram to rapidly drive the punch away from the die following said exhausting of high-pressure fluid, and means for subsequently operating said valves to the siad respective positions including means for thereafter shifting said first valve to said first position for redirecting fluid from said high-pressure source to said cushion ram so as to eject a blank in said die.

2. In a hydraulic press having a fixed die surrounding a shiftable die cushion and a movable punch sunrounded by a relatively shiftable clamping plate, the combination comprising, a cushion ram for holding said cushion, a double-acting main ram for driving said punch toward said fixed die, a clamping ram carried by said main ram for urging said clamping plate towards said fixed die, a low-pressure, high-volume source of fluid under pressure including a first pump and a first accumulator, a highpressure source of fluid under pressure including a second pump and a second accumulator, means for directing fluid from said high-pressure source to said clamping ram at a preset pressure, means including a first valve having a first position for directing fluid from said high-pressure source to said cushion ram at a second preset pressure, means including a second valve having a first position for thereafter directing fluid from said low-pressure source to said main ram to rapidly drive said punch and said clamping plate toward said die, means including a third valve having a first position for directing fluid from said high-pressure source to said main ram as said punch reaches said stock so as to drive the punch into the stock against the resistance of said cushion ram, one way valve means responsive to said high pressure in said main cylinder for shutting off flow from said low-pressure source and thus permit said first pump to charge said first accumulator, said first and second valves each having a second position for exhausting high-pressure fluid from said main ram and said cushion ram following movement of said punch into said stock, said second valve having a third position for directing fluid from said low-pressure source to said main ram to rapidly drive the punch away from the die following said exhausting of high-pressure fluid, said third valve having a second position effective to shut off flow from said high-pressure source to said main ram and thus permit said second pump to charge said second accumulator, and means for thereafter shifting said first valve to said first position for redirecting fluid from said high-pressure source to said cushion ram so as to eject a blank away from said die.

3. In a hydraulic press having a fixed die surrounding a shiftable die cushion and a movable punch surrounded by a relatively shiftable clamping plate, the combination comprising, a cushion ram for holding said cushion level with said die, a double-acting main ram for driving said punch toward said fixed die, a clamping ram carried by said main ram for urging said clamping plate towards said fixed die, a low-pressure, high-volume source of fluid under pressure, a high-pressure source of fluid under pressure, means for directing fluid from said high-pressure source to said clamping ram at a predetermined pressure, means including a first valve element for directing fluid from said high pressure source to said cushion ram, means including a second valve element for thereafter directing fluid from said low-pressure source to said main ram to rapidly drive said punch and said clamping plate toward said die, means including a third 'valve element for directing fluid from said high-pressure source to said main ram as said punch reaches the stock so as to drive the punch into the stock against the resistance of said cushion ram, means including fourth and fifth valve elements for exhausting high-pressure fluid from said main ram and said cushion ram following movement of said punch into the stock, means including a sixth valve element for directing fluid from said low-pressure source to said main ram to rapidly drive the punch away from the die following said exhausting of high-pressure fluid, cam follower means associated with each of said valve elements and a plurality of cams on a driven cam shaft coacting therewith for exactly timing and operating said valve elements in numerical sequence and subsequently operating said first valve element a second time for redirecting fluid from said high pressure source to said cushion ram so as to eject a blank from said die.

4. In a hydraulic press having a fixed die surrounding a shiftable die cushion and a movable punch surrounded by a relatively shiftable clamping plate, the combination comprising a cushion ram for holding said cushion level with said die, a double-acting main ram for driving said punch toward said fixed die, a clamping ram carried by said main ram for urging said clamping plate towards said fixed die, a low-pressure, high-volume source of fluid under pressure, conduit means for directing fluid from under pressure, a high-pressure source of fluid said highpressure source to said clamping ram, first flow control means for directing fluid from said high-pressure source to said cushion ram, second flow control, means for thereafter directing fluid from said low-pressure source to said main ram to rapidly drive said punch and said clamping plate toward said die, third flow control means for directing fluid from said high-pressure source to said main ram as said punch reaches the stock so as to drive the punch into the stock against the resistance of said cushion ram, fourth flow control means for exhausting high-pressure fluid from said main ram and said cushion ram following movement of said punch into the stock, fifth flow control means for directing fluid from said low-pressure source to said main ram to rapidly drive the punch away from the die following said exhausting of high-pressure fluid, cam means for sequentially operating said flow control means in numerical order and thereafter again operating said first flow control means for redirecting fluid from said high-pressure source to said cushion ram so as to eject the blank from said die, and means for exactly controlling the fluid pressures acting on said (clamping and cushion rams so as to regulate the compression forces exerted on stock material being blanked in said press.

References Cited in the file of this patent UNITED STATES PATENTS 860,009 Becker July 16, 1907 1,625,748 Schiess Apr. 19, 1927 1,649,427 Walp Nov. 15, 1927 2,694,820 Fitzgerald Nov. 23, 1954 2,758,652 Novinger Aug. 14, 1956 2,825,405 Maass Mar. 4, 1958 2,914,981 Roeber Dec. 1, 1959 FOREIGN PATENTS 568,225 Canada Dec. 30, 1958 

3. IN A HYDRAULIC PRESS HAVING A FIXED DIE SURROUNDING A SHIFTABLE DIE CUSHION AND A MOVABLE PUNCH SURROUNDED BY A RELATIVELY SHIFTABLE CLAMPING PLATE, THE COMBINATION COMPRISING A CUSHION RAM FOR HOLDING SAID CUSHION LEVEL WITH SAID DIE, A DOUBLE-ACTING MAIN RAM FOR DRIVING SAID PUNCH TOWARD SAID FIXED DIE, A CLAMPING RAM CARRIED BY SAID MAIN RAM FOR URGING SAID CLAMPING PLATE TOWARDS SAID FIXED DIE, A LOW-PRESSURE, HIGH-VOLUME SOURCE OF FLUID UNDER PRESSURE, A HIGH-PRESSURE SOURCE OF FLUID UNDER PRESSURE, MEANS FOR DIRECTING FLUID FROM SAID HIGH-PRESSURE SOURCE TO SAID CLAMPING RAM AT A PREDETERMINED PRESSURE, MEANS INCLUDING A FIRST VALVE ELEMENT FOR DIRECTING FLUID FROM SAID HIGH PRESSURE SOURCE TO SAID CUSHION RAM, MEANS INCLUDING A SECOND VALVE ELEMENT FOR THEREAFTER DIRECTING FLUID FROM SAID LOW-PRESSURE SOURCE TO SAID MAIN RAM TO RAPIDLY DRIVE SAID PUNCH AND SAID CLAMPING PLATE TOWARD SAID DIE, MEANS INCLUDING A THIRD VALVE ELEMENT FOR DIRECTING FLUID FROM SAID HIGH-PRESSURE SOURCE TO SAID MAIN RAM AS SAID PUCNCH REACHES THE STOCK SO AS TO DRIVE THE PUNCH INTO THE STOCK AGAINST THE RESISTANCE OF SAID CUSHION RAM, MEANS INCLUDING FOURTH AND FIFTH VALVE ELE- 